In view of the global responsibility
to protect the environment, the Euroemission Standards
are introduced in Europe to progressively reduce the
amount of harmful pollutants, such as carbon monoxide,
hydrocarbons, nitrogen oxides and particulates, found in
engine exhaust.

The 2000/2005 standards were
accompanied by an introduction of more stringent fuel
quality rules that require minimum diesel cetane number
of 51 (year 2000), maximum diesel sulfur content of 350
ppm in 2000 and 50 ppm in 2005, and maximum petrol
(gasoline) sulfur content of 150 ppm in 2000 and 50 ppm
in 2005.

"Our research tends
to focus on diffuse emissions, those that are difficult
to characterize because they don't come from a single
point, say, the tail pipe. What we essentially do is look
at the net sum of emissions coming from vehicles and
compare them to the EPA model that estimates the
individual components and we add them up to see if the
real world data conform to what the models predict."